Usage:
D346, D349 Truck Engines;
D348 Vehicle Engines;
776 Tractors;
777 Trucks
Description of Change: Several improvements have been made to the aftercooler water lines used on the above models, as follows:
... The line from the pump to the aftercooler tee and elbows is now held in position by separate clamp straps. Formerly, support straps were welded to the tube, but these caused stresses which broke the tube in some installations. The new straps permit more tolerance during installation, without stress.
... A short pipe is now used at the pump end of the line to the aftercooler, with an O-ring seal between the pipe and the new tube. This is the same type connection as is used at the aftercooler end of the line, and also improves the tolerance for differences in specific installations to prevent possible stresses. A heat shield is added around this connection to prevent possible seal damage from high temperatures.
... At the aftercooler end of the water line, a new tee and elbows are made of iron instead of brass. The iron components will have a lower rate of wear from normal vibration, and give longer service life.
... On engines equipped with attachment water lines to use jacket water in the aftercoolers, similar changes are made. A new tube assembly is used, with separate clamp straps to prevent stresses. Also, the tube used in the new assembly is now made in one piece, in comparison with the former tube which was fabricated from separate parts. This makes a stronger tube assembly for increased service life.
Adaptable As: Direct replacement when the necessary parts are used together. For reference, engines equipped with standard aftercooler water lines have a separate water pump for the aftercooler circuit; engines equipped with the attachment aftercooler lines group for jacket water do not have the separate water pump.
